Broadway is said to bet on stars. Well, yes and no. Look at the long-running hits: Do you know who’s in “Wicked” or “Jersey Boys” right now? At the same time, casting is key to the equation, and meddling with it definitely impacts the overall vibe. Sometimes a new lead’s better, sometimes worse — and sometimes, it just creates a different mood.

So let’s revisit three musicals to see how their new leads are working out.

Sutton Foster was a lot of fun in “Anything Goes,” and won a Tony for her performance — even though her wholesome, gee-whiz persona was at odds with the part of brassy nightclub singer Reno Sweeney.

Foster’s replacement, Stephanie J. Block, sure can play dames. An alum from “9 to 5” and “The Pirate Queen,” this powerful belter has womanly charms, as opposed to Foster’s coltish appeal. Her Reno’s been around the block, and you can tell she enjoyed every minute of the trip.

But at a recent matinee, Block looked as if she were holding back. She needs to let her hair down a little more — those who saw her campy turn as a 1930s movie star in the comedy “By the Way, Meet Vera Stark” know she has it in her.

Overall, the show still looks very good. Bill English is better than the original male lead as impoverished broker Billy Crocker — and the Act I finale remains the most fun in town.

Verdict: It’s worth a trip if you haven’t seen this Cole Porter goodie.

As “Chicago” proves time and time again, you don’t need stage experience to set the box office on fire.

An unknown named Patina Miller was first cast as Deloris van Cartier, the Whoopi Goldberg role, in “Sister Act.” Now the audience screams when Deloris takes the stage. That’s because she’s played by Raven-Symoné, the Disney Channel star of “That’s So Raven” and “The Cheetah Girls.”

Endowed with a thin but pleasant pop voice, Raven-Symoné doesn’t own the stage the way Miller did as a sassy, sexy 1970s lounge act. Luckily, she’s more comfortable when Deloris goes undercover in a convent.

In any case, the book is so funny, the score so infectious that they help this nun fly.

Raven-Symoné also gets solid support from Carolee Carmello, who took over from Victoria Clark as the Mother Superior. This Broadway vet (“The Addams Family,” “Mamma Mia!”) confidently nails every joke.

Verdict: Broadway’s single most happy-making musical is almost novice-proof.

Broadway Theatre, 1681 Broadway; 212-239-6200. Through Aug. 26.

‘Memphis” is a textbook example of how a new lead’s drastically different take on a part can affect a partner.

The Tony-nominated Chad Kimball had a sneaky charm as Huey Calhoun, making that disc jockey a bit of a colorful hustler.

Adam Pascal — Roger, the romantic, HIV-positive guitarist in the original “Rent” — plays Huey like an overgrown eager beaver, goofily enthusiastic about the R&B music he spins on the radio.

As a consequence, Huey has zero sexual zing with Montego Glover’s Felicia, the aspiring singer. Maybe to compensate, Glover now overacts broadly, a caricature of the nuanced performer she was in the early days.

On the plus side, though, Pascal sings beautifully — his incredible rendition of “Memphis Lives in Me” is a real tear-jerker.

Verdict: Those who’ve seen “Memphis” before may find a return trip worthwhile. Newbies will enjoy the singing and dancing, still tight and energetic 2 1/2 years after opening night.